Tool for a street milling, coal-cutting or mining machine

ABSTRACT

A tool for a street milling, coal-cutting mining machine or the like which includes a chisel with a chisel head and a chisel stem. The chisel stem is rotatably mounted in a receiver of a chisel holder. A perforated wearing protection element is mounted on the chisel head. The chisel head sits closely on the chisel holder while embracing the interposed wearing protection element. This invention achieves improved wearing protection behavior of such a tool. Thus, the inventive wearing protection element has one or more spring elements that elastically support the chisel head by way of the chisel holder.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a tool for a street milling, coal-cutting,mining machine or the like which has a chisel with a chisel head and achisel shaft. The chisel shaft is rotatably mounted in a receiver of achisel holder. A perforated wear protection element is mounted on thechisel head with the chisel head sitting closely on the chisel holderwith the wear protection element interposed.

2. Description of Related Art

A tool is known from European Patent Reference EP 0 413 917 A1, wherethe wear protection element is formed as a circular steel sheet disk,from which an opening is punched in the center. The opening is extendedin the direction of the chisel head. A chamfered part of the chisel headlies in this extension. The wear protection element lies flat on acontact surface of the chisel holder. During use of the tool, wastematerial can get past the chisel head and the wear protection elementand reach the receiver. In this position, this material can block thefree rotation of the chisel.

Another tool for mounting a chisel on a chisel holder is known fromEuropean Patent Reference EP 0 200 37 B1, where the chisel head is setdirectly on the chisel holder. The chisel holder is designed to be underspring tension on a base part that can be attached on its side to amilling roller. The chisel can also become fixed due to waste materialpenetrating into the receiver, and then the chisel can no longer rotatefreely.

SUMMARY OF THE INVENTION

One object of this invention is to provide a tool of the above mentionedtype, which has good wear behavior.

The wear protection element comprises one or more spring elements thatelastically support the chisel head relative to the chisel holder.

Due to the spring-tensioned support of the chisel head, intermittentforces acting on the chisel are damped so that excessive materialstresses are prevented. In addition, the spring force provides an axialplay for the chisel, wherein the chisel head can then also move axiallyin the receiver of the chisel holder. With this axial play, there is atype of “pump effect” which can extract waste material that has reachedthe region of the receiver. Thus, the free rotation of the chisel can bemaintained.

In order to keep the cost of parts and assembly to a minimum, accordingto a preferred embodiment of this invention, spring elements are formedintegrally with the wear element.

In one possible embodiment of this invention, the wear protectionelement comprises a base part with at least one flat contact surfacethat contacts an opposing surface of the chisel head or the chiselholder. A circumferential section acting as a spring element is bent inthe direction of the chisel holder or the chisel head from the basepart. The spring element supports the chisel holder or the chisel headon the region of the spring element facing away from the base part.

However, it is also conceivable for several, preferably three, springelements that are separated from each other to be bent from the basepart. With these spring elements, a definite, statically determinatesupport situation is achieved.

In order to be able to achieve progressive or regressive springcharacteristics, according to one embodiment of this invention, eachspring element comprises two or more spring sections that exhibitdifferent spring rigidity and/or the same or different springdeflections.

A tool according to this invention has an area around the opening inwhich the chisel shaft is inserted, with a circumferential centeringattachment that projects in the direction of the chisel holder and thatinteracts with a centering extension of the receiver of the chiselholder. The centering extension of the chisel holder simplifies assemblyof the chisel shaft in the receiver. During operation, the region of thecontact surface on which the wear protection element is supported andwhich is arranged around the receiver gradually wears away. This iscaused by rotation of the wear protection element on this contactsurface. With a centering attachment at the wear protection element, thecentering extension is worn away to the same degree as the contactsurface. However, this causes the centering extension to remain inplace.

A tool with a simple configuration and that is cost-effective to produceis obtained according to this invention when the wear element isproduced as a stamped, bent part from a flat material blank, from whichthe opening for the chisel shaft is punched and whose edge or edges arebent for completely or partially forming the spring elements.

Here, one or more reinforcing ribs can be formed on the edges that formthe spring elements. The reinforcing ribs increase the spring rigidity.Thus, a relatively low material strength can be used for the wearprotection element yet still provide a high spring rate.

BRIEF DESCRIPTION OF THE DRAWINGS

This invention is explained in more detail in view of the drawings,wherein:

FIG. 1 is a chisel holder with an attached tool in a side view andpartial cross section;

FIG. 2a is a wear protection element in a side view and partial crosssection;

FIG. 2b is the wear protection element from FIG. 2a in a top view;

FIG. 3a is another embodiment of a wear protection element in a sideview and a partial cross section;

FIG. 3b is the sear protection element from FIG. 3a in a top view;

FIG. 4a is a modification of the wear protection element shown in FIGS.3a and 3 b in a side view and partial cross section; and

FIG. 4b is the wear protection element of FIG. 4a in a top view.

DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 shows a chisel holder 20 with a base part 22. The base part 22carries a plug attachment 21 that can fix the chisel holder 20 to aholder part so that it can be removed. The holder part can then beattached to a milling roller or a coal-cutting machine or the like. Forthe sake of clarity, the holder part and the milling roller are notshown in FIG. 1. The base part 22 has a receiver 23. The receiver 23 isbored into the base part 22 starting from a level contact surface 24.The receiver 23 expands outwards by means of a centering extension 25 atthe contact surface 24. A chisel 10 is fixed to the chisel holder 20.The chisel 10 comprises a chisel head 11 and a chisel shaft 15. Thechisel head 11 has a receiver on its front side, in which a bit 12 issoldered. In an intermediate region, the chisel head 11 has acircumferential groove 13 that enables the disassembly of the chisel 10from the chisel holder 20, with a tool. In the transition region to thechisel shaft 15, the chisel head 11 is sealed with a flange 14. As shownin FIG. 1, an adapter sleeve 16 is mounted on the chisel shaft 15. Theadapter sleeve 16 holds the chisel 10 in the axial direction.Furthermore, the adapter sleeve 16 is braced due to radial expansion inthe receiver 23 of the chisel holder 20. In this way, the adapter sleeve16 holds the chisel 10 in the chisel holder 20, wherein the chisel 10can freely rotate in the adapter sleeve 16. Between the chisel head 11and the chisel holder 20 there is a wear protection element 30. The wearprotection element 30 supports the chisel head 11 on the contact surface24 of the chisel holder 20.

The wear protection element 30 is produced as a stamped, bent part froma circular steel sheet blank and has a centering opening 35, by whichthe wear protection element 30 is mounted on the chisel shaft 15. In aregion facing the chisel head 11, the opening 35 tapers into anexpanding, chamfered inlet 37. The chamfered inlet 37 serves for easierassembly of the wear protection element 30. The wear protection element30 is initially loaded onto the end of the adapter sleeve 16 with itschamfered inlet 37 facing away from the chisel head 11. Thus, thediameter ratio of the opening 35 of the wear protection element 30relative to the tensioned diameter of the adapter sleeve 16 is selectedso that the adapter sleeve can be inserted into the receiver 23 withminimum or no force. For final assembly of the chisel 10, the wearprotection element 30 is shifted by the application of force, forexample, by means of hammer blows, along the adapter sleeve 16 until itgoes beyond the end of the adapter sleeve 16 on the side of the chiselhead. Then the adapter sleeve 16 is snapped in radially and is tensionedin the receiver 23. In this assembled position, the chisel head 11contacts the contact surface 36 of the wear protection element 30. Thecontact surface 36 extends perpendicularly to the center longitudinalaxis of the chisel 10 and connects to the chamfered inlet 37. In theregion of this contact surface 36, the wear protection element 30 formsa base part, from which a spring element 32 is bent projecting outwards.The spring element 32 is formed from the outer edge of the wearprotection element 30 which is placed at an angle to the contact surface24 of the chisel holder 20. The spring element 32 is supported at itsend facing away from chisel head 11 by means of a support section 31 onthe contact surface 24 of the chisel head 20. As shown in FIG. 1, thewear element 30 has a circumferential centering attachment 33 designedwith a geometry that makes a 45° angle with the chisel holder 20,wherein this angle continues around the receiver 23 as the centeringextension 25. The centering extension 25 simplifies mounting of thechisel 10 in the receiver 23. As shown in FIG. 1, the centeringattachment 33 in its original state, not attached to the tool, isarranged at a distance to the centering extension 25. This separationcreates a spring deflection. If a tool, for example for a road surface,is attached to the tool of this invention, then the impact of the bit onthe material to be removed is cushioned by the spring element 32 of thewear protection element. In this way, excessive material stresses on thebit 12 are prevented. During the removal process, the wear protectionelement 30 is flattened. After the tool is detached, the wear protectionelement 30 springs back into its output position, wherein the chiselshaft 15 is shifted along its axial direction in the receiver 23. Due tothis “pump effect,” waste material which gets past the chisel head 11and the wear protection element 30 and reaches the receiver 23 can beextracted. Thus, the free rotation of the chisel 10 in the adaptersleeve 16 is maintained.

In the following, various embodiments of wear protection elements 30 areexplained in view of FIGS. 2a-4 b.

The wear protection element shown in FIGS. 2a and 2 b has a springelement 32 that is formed from the outer edge of the wear protectionelement 30. The edge of the wear protection element 30 is bent so thatit runs parallel to the longitudinal extension of the chisel 10. Thisproduces a flat, annular support section 31, by which the wearprotection element 30 is supported on the contact surface 24.

A wear protection element 30 is shown in FIGS. 3a and 3 b, having anouter edge not bent 90° as shown in FIGS. 2a and 2 b, but rather at anangle less than 90°.

In FIGS. 4a and 4 b, the wear protection element 30 in FIG. 1 is shownin more detail. The outer edge that forms the spring element 32 hasreinforcing ribs 34. The spring rate of the spring element 32 can beincreased by these reinforcing ribs 34.

The production of the wear protection element 30 described above issimple. Here, a circular blank is first punched from a flat steel sheetblank. The opening 35 can be punched from the steel sheet blank. Thenthe region surrounding the opening 35 is stamped-so that the centeringattachment 33 and the chamfered inlet 37 are obtained simultaneously.Then the spring element 32 is bent.

What is claimed is:
 1. In a tool for a milling, cutting, or miningmachine, having a chisel head and a chisel shaft, wherein a chisel isrotatably mounted in a receiver of a chisel holder, a perforated wearprotection element is mounted on the chisel head with the chisel headsitting closely on the chisel holder with a wear protection elementinterposed, the improvement comprising: the wear protection element (30)having at least one spring element (32) elastically supporting thechisel head (11) relative to the chisel holder (20), the wear protectionelement (30) having a base part with at least one flat contact surfacethat contacts an opposing surface of one of the chisel head (11) and thechisel holder (20), at least two of the spring elements (32) bent fromthe base part in the direction of one of the chisel holder (20) and thechisel head (11), and the spring elements (32) supporting one of thechisel holder (20) and the chisel head (11) in a region of the springelements (32) facing away from the base part (22).
 2. In the toolaccording to claim 1, wherein the at least one spring element (32) isintegrally formed with the wear element (30).
 3. In the tool accordingto claim 2, wherein the wear protection element (30) has a base part(22) with at least one flat contact surface (36) that contacts anopposing surface of one of the chisel head (11) and the chisel holder(20), a circumferential section serving as a spring element (32) is bentfrom the base part in a direction of one of the chisel holder (20) andthe chisel head (11), and the spring element (32) supports one of thechisel holder (20) and the chisel head (11) in a region of the springelement (32) facing away from the base part (22).
 4. In the toolaccording to claim 3, wherein the spring element (32) has at least twospring sections with different spring rigidities.
 5. In the toolaccording to claim 4, wherein near an opening (35) in which the chiselshaft (15) is inserted a circumferential centering attachment (33)projects towards the chisel holder (20) and interacts with a centeringextension (25) of the receiver (23) of the chisel holder (20).
 6. In thetool according to claim 5, wherein the wear protection element (30) isproduced as a stamped, bent part from a flat material blank, from whichthe opening (35) is punched for the chisel shaft (15) and has at leastone edge bent for at least partially forming the spring elements (32).7. In the tool according to claim 6, wherein at least one reinforcingrib (34) is formed on edges that form the spring elements (32).
 8. In atool for a milling, cutting, or mining machine, having a chisel head anda chisel shaft, wherein a chisel is rotatably mounted in a receiver of achisel holder, a perforated wear protection element is mounted on thechisel head with the chisel head sitting closely on the chisel holderwith a wear protection element interposed, the improvement comprising:the wear protection element (30) having at least one spring element (32)elastically supporting the chisel head (11) relative to the chiselholder (20), and the spring element (32) having at least two springsections with different spring rigidities.
 9. In the tool according toclaim 8, wherein the wear protection element (30) has a base part withat least one flat contact surface that contacts an opposing surface ofone of the chisel head (11) and the chisel holder (20), and at least twoof the spring elements (32) are bent from the base part in the directionof one of the chisel holder (20) and the chisel head (11), and thespring elements (32) support one of the chisel holder (20) and thechisel head (11) in the region of the spring elements (32) facing awayfrom the base part (22).
 10. In the tool according to claim 8, whereinthe wear protection element (30) has a base part (22) with at least oneflat contact surface (36) that contacts an opposing surface of one ofthe chisel head (11) and the chisel holder (20), a circumferentialsection serving as a spring element (32) is bent from the base part in adirection of one of the chisel holder (20) and the chisel head (11), andthe spring element (32) supports one of the chisel holder (20) and thechisel head (11) in a region of the spring element (32) facing away fromthe base part (22).
 11. In the tool according to claim 8, wherein nearan opening (35) in which the chisel shaft (15) is inserted acircumferential centering attachment (33) projects towards the chiselholder (20) and interacts with a centering extension (25) of thereceiver (23) of the chisel holder (20).
 12. In the tool according toclaim 8, wherein the wear protection element (30) is produced as astamped, bent part from a flat material blank, from which an opening(35) is punched for the chisel shaft (15) and has at least one edge bentfor at least partially forming the spring elements (32).